1. Field of Invention
The present invention relates to a porous bio-material that can be implanted into a human body and a method of preparation thereof, and more particularly to a porous bio-material with controllable pores, which is adapted to the human body and has relatively high strength, and a method of preparation thereof.
2. Related Art
Bio-ceramics are frequently made of ceramic particles. The sizes of particles of the typical ceramic powder are usually smaller than 10 microns. When the ceramic particles are stacked together, the size of the pores between the particles is also smaller than 10 microns. The pore in the sintered body may even become smaller. The small pores cannot allow white blood corpuscles to pass through and thus cannot be adapted as the artificial bone material.
One conventional method for implanting big pores into the ceramic material is adding artificial polymeric material (e.g., PMMA, PE, PS or the like) to the ceramic powder to form a body, and then to place the body at a temperature higher than 600 degrees centigrade. At this time, the artificial polymeric material slowly disappears due to the high temperature, and the porous ceramic body is left behind. For this fabrication process, there is a limit for the artificial polymeric material to be added. As the amount of the artificial polymer is higher than the limit, the ceramic body may collapse as the artificial polymeric material is being burned off so that the desired product cannot be obtained. If the amount of the artificial polymeric material is low and the amount of ceramic powder is high, the big pores left behind by removing the artificial polymeric material are usually enclosed by the ceramic powder, and the pores exposed at the surface of porous ceramic are consequently smaller so that the blood cannot easily flow.
Another conventional method for implanting big pores into the ceramic material is mainly to use an artificial polymeric sponge as a template, to coat a ceramic slurry onto the artificial polymeric sponge, and then to burn off the artificial polymeric sponge to a temperature higher than 600 degrees centigrade so that the porous body with porosity over 90% can be obtained. The sizes of the pores formed in this process can reach several millimeters as resulted from the large pores of the sponge. However, the drawback is that the strength of the porous ceramic material is usually low because of its large amount of large pores. Furthermore, because only several sizes of the pores are available for the artificial polymeric sponge, only several sizes for the pores in the porous ceramic material are possible.